EP-A-1658973 discloses a packaging film providing some oxygen permeability for packaging food products requiring oxygen permeability.
WO-A-2006/011842 describes a rigid permeable packaging material for perishables having a microbiological activity, the packaging material providing a carbon dioxide gas barrier and an oxygen gas barrier that can be controlled independently of the thickness of the packaging material.
Flexible bags made of plastic material may be used for the inner bag of bag-in box packages. Hereby, a flexible bag is inserted into an outer box made of cardboard material. Those packages offer the advantage that the cardboard can be easily printed and, after use, can be folded flat and recycled. Furthermore, those packages usually have a form which allows good product presentation on the retailer shelves.
U.S. Pat. No. 5,203,470 describes a bag-in-box composite container for storing and pouring out liquids as e.g. milk or wine. Those containers consist basically of a plastic inner bag having a pouring spout within a sturdy outer paperboard box.
Contaminants diffusing through the plastic inner bag may become a problem, especially when using recycled paperboard, cardboard or carton material. Over the past few years there has been a growing awareness and concern regarding contaminants in recycled board materials, or printing inks as well as other external environment contaminants migrating into food products.
For bag-in-box food packages where recycled paperboard, cardboard or carton is used for economical and logistical reasons to produce the outer box and where the inner bag material does not provide a functional barrier to volatile contaminants migrating out of the paperboard box a particular problem may be caused by hydro-carbon mineral oils as e.g MOSH (mineral oil saturated hydrocarbons), a typical volatile contaminant comprised in recycled paperboard material. In such circumstances, the food product may become contaminated and yielded unfit for consumption. For reducing this problem an outer box material made of virgin paperboard may be used, but this may incur significant extra costs and may also result in possible supply problems as virgin board is often in global short supply. Furthermore, volatile contaminants (sometimes just named volatiles) can also come from the printing inks used on the cartons.
As an alternative to prevent migration of contaminants into the food of a bag-in-box package, the inner bag may be manufactured from a high barrier complex laminate. Such an inner bag would typically consist of a multi process laminate structure containing two or more individual film and/or foil layers. Aluminium or other oxide based barrier layers would typical be incorporated. Such structures would generally require a multiple process manufacturing regime with all the inherent costs and environmental impacts. A known material used to date as good barrier material is a metallised laminate with typically 18 μm metallised OPP/35 μm HDPE-Surlyn. Even if such a laminate solves some problems, it would not be useable for some dry food packages as e.g. the majority of cereal products, because most of those cereals need to ‘breath’, but a metallised OPP/HDPE laminate is a high oxygen barrier which does not allow the required breathability to take place.